DE2303890C2 - Process for heating liquid food - Google Patents

Description

Solutions or viscous suspensions, such as, for example, milk, soups, sauces, desserts or baby foods, and can optionally contain discrete solid particles.

The term "liquid food" as used herein also includes slurries or suspensions containing discrete particulate matter. The dry matter content of the liquid to be treated can for example be up to about 50% by weight, with the remainder consisting essentially of water product to be treated selected For the sterilization of food products, for example, the preheating temperature can conveniently be slightly above 10X) ⁰ C if the preselected pressure is atmospheric pressure and if the time / temperature relationship for individual products is selected so that sufficient sterility is obtained.

In the drawing is a system for schematically Implementation of the method according to the invention shown.

The product to be treated is supplied by a Rejarvoir 1 withdrawn through a line 2 and passed through a pump 3 and a line 4 to a preheater 5 The The preheater is preferably a direct steam heater and is supplied with steam through a line 6 Preheated product exits through a line 7 and passes through a pressure reducing valve 8, which is located in the Line is located in an expansion chamber 9. A temperature sensor / controller 10 in line 7 controls the Preheater 5 such that the temperature to which the product is preheated is kept substantially constant.

A substantially constant predetermined level of product is maintained in the expansion chamber 9, with the help of a level meter 11, which controls the pump 3 The expansion chamber 9 can through a line 12 to atmospheric pressure be held when a valve 13 is open, but in Depending on the nature of the product to be treated, the pressure in this chamber can be below or below above atmospheric pressure. So when working at temperatures below 100 ° C in the chamber 9 a sub-atmospheric pressure can be maintained by using a suitable vacuum source the line ί 2 is connected. Similarly, if boiling temperatures above 100 ° C are desired, by adjusting the valve 13, a positive pressure can be maintained in the chamber 9. The preheated Product entering the expansion chamber is subjected to a rapid and predetermined pressure drop, which is the evaporation of some of the water and also the removal of gases and volatiles Substances caused to be drained through the line 12. By expanding on their Boiling temperature at the preselected pressure (usually atmospheric pressure) in the chamber 9 prevails, the product is also cooled, whereby a supply of preheated product with a constant temperature, generally around 100 ° C, is obtained. The preheated product is made from the Chamber 9 withdrawn through a line 14 and is at a constant flow rate through a pump 15 passed through a line 16 to a heater 17 where it is errii'zt, usually to at least 130 ° C. In line 16 is through a regulator 18 acting on the pump 15 maintains a constant flow rate. The heater 17 can either be a direct steam injection heater or a direct heat exchanger The latter is preferred. Whatever type of heater is used, it will come with one constant speed through a line 19 with a heating medium, such as. B. steam fed wherein the supply of the heating medium through a

Controller 20 is regulated.

The heated product exits through a line 21. Its temperature is measured by a controller 22, which acts on a three-way valve 23 under the valve allows it to operate under normal operating conditions

is 23 that the product from the line 21 into a line 25 flows which leads to a storage section 26, but the regulator 22 is set so that it is any product whose temperature deviates from a predetermined value from the system promoted by opening the valve 23 so that it is in communication with a discharge line 24 Avoid heat loss through evaporative cooling, When the valve 23 is set to distribution, there is a pressure reducing valve 42 in the discharge line 24 switched on to maintain a pressure in this line which is essentially equal to that

Pressure is that under normal conditions in the heater

17 and in line 21 prevails

After the storage section, the product

in a heat exchanger 27 below 50 ° C, preferably about 40 ° C, cooled and then passes through a Line 28 into a storage reservoir 29. In the reservoir 29, a positive gas pressure is applied to the product a pressure regulator 30 maintained on a valve 31 in a gas supply line 32 and a Drain valve 44 in a gas outlet line 45 acts

Under normal operating conditions, product is passed through a line 33, a three-way valve 46 and a Line 47, which leads to the filling device, is withdrawn from the reservoir 29. Flow during pre-sterilization Liquids used to clean or sterilize the device from reservoir 29 through the line 33, the valve 46, a line 48, a liquid seal 34, a valve 51 and a Line 35. An exit valve 52 is provided which allows a small amount of gas to pass through allowing liquid to pass through the liquid seal. Of the The purpose of the liquid seal is that

so these fluids can be removed from the system without loss of gas pressure in the reservoir. Of the Liquid seal can be designed to contain fine solids when switching from non-product liquid can go through on product.

The device also has a storage tank 36 for water, which is preferably plasticized, and which is preferably kept at a constant temperature. During normal operation, a valve 38 and a Three-way valve 39 to line 14 open. Should an error occur for any of the reasons explained above occur, and particularly when the level of product in reservoir 29 has reached a predetermined high If levels are reached as measured by cell 50 then valves 38 and 39 are returned to tank 36 or opened to a line 49 so that water is admitted into the system. The valves 38 and 39 are automatically operated >> o there is water in the system can reach, which then through a valve 40, which

a certain time after the valves 38 and 39 is actuated, can expire. This enables im essentially all of the product from the system can be collected in reservoir 29. Water, which is heated and sterilized by the heater 17 and cooled by the heat exchanger 27, runs through a line 41 and a pressure reducing valve 43 from the plant, so that the device is heated in one sterile condition can be maintained until the error is corrected, after which a switch to normal Operation is achieved quickly by actuating valves 38, 39 and 40 in the reverse sequence.

Volatile components or other flavor components that are used for reasons of flavoring or for other reasons can be injected into the system through a valve 37 in line 16 will. Solids in suspension can also be introduced in the same manner. The valve 37 preferably works in stages with valves 38 and 39. It is normally open when the product is through the system is running, and closed when water is running through the system, d. H. during a shutdown or during pre-sterilization.

Since solids and liquids have different heat treatments in terms of time and temperature For example, in order to achieve sterility, it may be preferable to use the solids preheat separately prior to injection into the liquid stream through valve 37.

The system can also use various measuring and display devices for temperatures and pressures exhibit. These are indicated in the drawing by the usual symbols.

The invention is illustrated by the following examples, in which the parts and percentages in Weight are expressed.

example 1

A milk-based dessert thickened with starch of the following composition is made:

Fresh milk
sugar

Disodium phosphate
vegetable fat
Carrageenan
modified starch
Flavoring agents and
Dyes

water

50.0%
7.0%
0.1%
1.7%
0.2%
5.0%

according to the
taste
ad 100%

The mixture is preheated to 49 ° C. in the reservoir 1 and then continuously to the steam injector 5 guided. Injection of steam into the product quickly raises the temperature of the product to 105 "C The heated product exits through line 7, in which the pressure reducing valve 8 is set so that an overpressure is created so that local relaxation in front of the valve is prevented. When mixing with the The steam condenses product, giving up its latent heat to the product. This condensate causes dilution of the product. When working out the recipe, this will be done accordingly considered

The product flows through the valve 8 and is in the container 9, which is at atmospheric pressure is set, relaxed through the discharge line 12 The product is partially due to the relaxation vented and there are certain volatile starch components, that are harmful to the end product are removed.

The product, which now has about 100 ^° C., collects in the container 9, from where it is continuously drawn off by the pump 15 at a constant speed. The level of the product in the container 9 is regulated by a pressure difference cell U,

ίο which influences the throughput of pump 3

The product, which has become viscous due to the swelling of the starch, is made by a magnetic one Flowometer 18 regulated, which regulates the speed of the pump 15, so that a constant throughput of 9.1 l / min is maintained.

The product is then fed into a heat exchanger 17 with a scraped surface, which is fed with steam at a constant pressure of 5 kg / cm ² so that it is heated to a temperature of 141 ° C. The heated product runs into the storage section 26, where it is held for 15 seconds before it is cooled to 40 ° C. in a second heat exchanger 27 with a scraped surface. The cooled product is stored in an aseptic reservoir 29 under nitrogen overpressure before it flows via line 47 to an aseptic filling unit, where it is filled into cans.

A bak> eriological examination of incubated jugs shows that the product is sterile.

Example 2

A baby food puree is made from 91 kg of spinach, which is driven through a 1.5 mm plate and with starch Eggs, fat and water were slurried

manufactured. After filling to 1361 slurry in the reservoir 1 is preheated to 50 ⁰ C and heated by steam injection at 104 ⁰ C after the steam injection, the slurry is cooled by expansion to 100 ° C in the expansion chamber, from where it with a constant flow rate of 9.1 l / min to an indirect heat exchanger with a roughened surface flows in the jacket of which a constant vapor pressure of 5 kg / cm ^{2 is} maintained. The slurry is thus heated to 136 ° C in the storage section and held at that temperature for 57 seconds before cooling to 42 ° C.

The sterilized product is filled into glass beakers under aseptic conditions

Example 3

The liquid component of a cream of a chicken soup is preheated in the reservoir 1 to 46 ° C, heated by steam injection to 104 ⁰ C and into the

Chamber 9 relax left where it is cooled to 100 ⁰ C.

The garnish (10 mm cubes from Chicken meat) suspended in a 1% starch gruel, in a ratio of 2 parts

Starch to 1 part solids. The suspension is preheated to 60 ⁰ C, then heated in an indirect heat exchanger to 121 ° C, and finally passed through a storage section that they after a period of 4 minutes at a temperature of 114 ° C leaving the suspension is then passed through the valve 37 introduced into the sterilization system at a constant rate of OJ l / min, where it is combined with the liquid component

The combined product is then fed at a constant rate of 9.1 l / min to the indirect heat exchanger 17, which is fed ^{with steam which has a constant pressure of 5 kg / cm 2.} The product is heated to 136 ° C and runs

through the storage section 26 where it remains for 57 seconds before being cooled to 42 ° C.

The cooled product is fed into reservoir 29 and canned under aseptic conditions bottled.

1 sheet of drawings

Claims (1)

Pntpntflnsnnich- ^{These cold mouths can therefore become} unsterile parts raieniansprucn. ^^ _Disappeared , with the plant Process for heating liquid food which is contaminated and bacterially unhealthy A further difficulty arises with the use of different viscosities on a product predetermined temperature, the liquid 5 HXS.T. systems, which for a continuous The main thing to be provided in an expansion chamber in dependent operation is the necessity that the ability of the pressure in the expansion chamber on sterile product emerging from the system, captured-boiling temperature is cooled and then turned into a gene if a tin error occurs on the filling machine Final heating to the predetermined heating level. Small tanks can be provided, but there is Tung temperature heated and a predetermined time io is generally not practicable, aseptic is kept at this temperature, thereby storage facilities of sufficient size characterized in that the preheated liquid for containing the product that is during a The ability to accumulate at a constant rate from the longer interruption must be provided. It is Expansion stage up to the final heating stage is therefore common in some systems, the product flows into the which can also be traced back at a constant speed with 15 system, which of course is a quality of his Heating medium results in constant heat loss or discard the product, is charged. * is of course uneconomical is A third solution is shut down the plant, but this means longer Delays in restarting the system Bring M back to working temperature and a Achieve sterility. The invention relates to a method for The object on which the invention is based is Heating liquid food. Creation of a process for the heat treatment of For the purpose of pasteurizing or sterilizing liquid foods, which are continuously long foods, in particular liquid foods, can be operated for a long time in which no parts are subjected to heating. You have to be careful about unwanted deviations in the product temperature, because on the one hand the door is heated and precautions for sterilization or pasteurization must be sufficient, but on the other hand the system in a sterile state can be heated to a proportionate and heated state for too long to be maintained when intermittently high temperatures must be avoided in order to prevent product flow due to delays or affect the taste and color of the food, either in the plant itself or in a shutdown. As a result, one has procedural related equipment such. B. a filling machine, facing ren, <r ^: e with HTST (high temperature - or an error occurs in the product feed
short time), the product being the subject of the invention, a method for heating liquid foods at a relatively high temperature for a short time - less than 1 minute - for example viscosities to a predetermined temperature 135 ° C - is heated. When using the liquid preheated in an expansion of these processes, it is of course important that the chamber is cooled to the boiling point in the specified temperature and time for the entire expansion chamber, depending on the pressure, and that the treated product is adhered to. The "o" were then carried out in a final heating stage to the most varied of predetermined attempts. For example, it is kept at this temperature for a continuous period of time, which process in which the heating is characterized by direct introduction of steam or a liquid with steam at a constant rate from the charged heat exchanger is customary, the 45 expansion stage flows up to the final heating stage, measure the product temperature and regulate the steam supply to the likewise charged at consunter speed with a maintenance of a constant temperature corresponding to the heating medium with constant heat content. In another process that becomes of the. DE-PS 1140 317 is known, the liquid in the process according to the invention is in the Food is first preheated in an expansion *> Expansion chamber to a constant temperature chamber by evaporation on a liquid food kept at constant pressure Cooled appropriate temperature and finally deducted and using a speed by introducing steam to the final heating medium, which is also constant Temperature brought. To avoid tempera- speed is fed, mixed thereby The temperature fluctuations in the device for the 55 results in a constant heating temperature and Perform this procedure beyond the steam heating time, which once set properly tongue device a three-way valve is provided, which does not require any regulation. The inventive is operated by a control device, which results in stable operation during long procedures insufficient heating the treated product in the times. The temperature control of the treated Returns expansion chamber. Disadvantageous to Regelsy- 60 product can be kept within about TC Stemen of this kind is their inevitable indolence, so become. The economy of operation is also that in procedures carried out with such systems it is important because the system is continuously connected to a ren it can happen that parts of the product to automatic switchover from product to water too much or too little. Can be operated if external systems are shorter This is particularly undesirable when viscous 65 time must be shut down. Products are processed, since product parts that have a The method according to the invention can be used for heat Temperature below the minimum acceptable treatment of a wide range of liquid food M. do not mix with the hotter product. medium products are used. these can